Generally speaking, a conventional scheme may employ a conventional protection circuit to protect a power source such as a battery. The conventional protection circuit may be used for disabling a system operating on a portable device or disabling a system application when the battery temperature is higher than a threshold, so as to achieve protection for the battery. The conventional protection circuit may be used for disabling the system when the battery voltage is lower than a minimum voltage threshold or the residual battery capacity is lower than a minimum capacity threshold, for protecting the battery.
The above-mentioned thresholds are usually configured and fixed for the battery before the battery goes out of the factory. However, characteristic of the battery may be changed after use. Accordingly, it is not appropriate to employ the conventional thresholds mentioned above for protecting the battery all the time. In addition, characteristic of the battery may be varied with other factors that are not considered by the conventional scheme. For precisely protecting the battery, it is not enough to merely consider voltage, battery capacity, or battery temperature.